Thermodynamic Channels
Evolution selects among paths that physics has already carved
Panel A — Naive view
Organisms (unconstrained)
Flat fitness landscape
Panel B — Thermodynamic reality
Valleys (viable channels)
Ridges (barriers)
Natural selection is powerful, but it is not free. Thermodynamics carves the valleys; selection chooses which valley to descend. The landscape exists before the organisms do. Evolution is a river finding channels, not a bird flying anywhere.